inhibition of calcitonin synthesis

In mammals, the major source of calcitonin is from the parafollicular or C cells in the thyroid gland, but it is also synthesized in a wide variety of other tissues, including the lung and intestinal tract.

PolyPeptide Group - Peptides, Peptide Synthesis and …

T1 - Stimulation of calcitonin synthesis and release in vitro by calcium and dibutyryl cyclic AMP

Calcium Metabolism and Metabolic Bone Disease

N2 - Previous studies established that in the rat, the uterus can accept a developing blastocyst for implantation only during a limited period of time on day 5 of gestation, termed the receptive phase. Our previous studies showed that the expression of calcitonin, a peptide hormone that regulates calcium homeostasis, is induced in rat uterus between days 3-5 of gestation and is switched off once the implantation process has progressed to day 6. In the present study, we analyze in detail how the expression of calcitonin messenger RNA (mRNA) in the uterus is regulated by the steroid hormones progesterone and estrogen and explore the possibility that calcitonin may serve as a potential marker of uterine receptivity. We demonstrate by in situ hybridization that calcitonin mRNA is synthesized specifically in the glandular epithelial cells between days 3-5 of pregnancy. Interestingly, calcitonin synthesis is also induced in these cells during pseudopregnancy, indicating that this peptide hormone is produced in the endometrium in response to maternal, rather than embryonic, signals. We also demonstrate that calcitonin mRNA expression during pseudopregnancy, like that in normal pregnancy, is under progesterone regulation. We further examined the steroid hormone regulation of uterine calcitonin expression in a delayed implantation model. In pregnant rats in which implantation is blocked upon removal of both ovaries on day 4 of gestation, continued administration of progesterone sustains calcitonin expression in the uterus for several days in the absence of estrogen. Administration of estrogen, which allows delayed implantation, also rapidly reduces calcitonin expression, indicating a role for this steroid hormone in turning off calcitonin gene expression. In gene transfection studies, expression of the progesterone receptor B isoform in cultured endometrial cells induces RNA synthesis from a reporter gene containing a 1.3-kb calcitonin promoter fragment in a hormone-dependent manner. As expected, mifepristone-complexed progesterone receptor B isoform fails to activate the calcitonin promoter. Progesterone acting through its nuclear receptor therefore regulates the expression of the calcitonin gene at the level of transcription. Finally, using RIA we investigated whether calcitonin is secreted from its glandular site of synthesis at the time of implantation by analyzing uterine flushings obtained from pregnant rats. We report the detection of a significant amount of calcitonin in the luminal secretions collected on day 4 and a lower amount on day 5 of gestation, whereas similar samples collected from animals on either day 3 or 6 of gestation did not contain detectable amounts of this peptide hormone. A transient burst of calcitonin secretion into the uterine lumen therefore occurs immediately preceding implantation. Based on these results, we propose that calcitonin is a measurable marker that forecasts the receptive state of rat endometrium during blastocyst implantation.

Melissa Kaplan's Herp Care Collection Last updated January 1, 2014

AB - Previous studies established that in the rat, the uterus can accept a developing blastocyst for implantation only during a limited period of time on day 5 of gestation, termed the receptive phase. Our previous studies showed that the expression of calcitonin, a peptide hormone that regulates calcium homeostasis, is induced in rat uterus between days 3-5 of gestation and is switched off once the implantation process has progressed to day 6. In the present study, we analyze in detail how the expression of calcitonin messenger RNA (mRNA) in the uterus is regulated by the steroid hormones progesterone and estrogen and explore the possibility that calcitonin may serve as a potential marker of uterine receptivity. We demonstrate by in situ hybridization that calcitonin mRNA is synthesized specifically in the glandular epithelial cells between days 3-5 of pregnancy. Interestingly, calcitonin synthesis is also induced in these cells during pseudopregnancy, indicating that this peptide hormone is produced in the endometrium in response to maternal, rather than embryonic, signals. We also demonstrate that calcitonin mRNA expression during pseudopregnancy, like that in normal pregnancy, is under progesterone regulation. We further examined the steroid hormone regulation of uterine calcitonin expression in a delayed implantation model. In pregnant rats in which implantation is blocked upon removal of both ovaries on day 4 of gestation, continued administration of progesterone sustains calcitonin expression in the uterus for several days in the absence of estrogen. Administration of estrogen, which allows delayed implantation, also rapidly reduces calcitonin expression, indicating a role for this steroid hormone in turning off calcitonin gene expression. In gene transfection studies, expression of the progesterone receptor B isoform in cultured endometrial cells induces RNA synthesis from a reporter gene containing a 1.3-kb calcitonin promoter fragment in a hormone-dependent manner. As expected, mifepristone-complexed progesterone receptor B isoform fails to activate the calcitonin promoter. Progesterone acting through its nuclear receptor therefore regulates the expression of the calcitonin gene at the level of transcription. Finally, using RIA we investigated whether calcitonin is secreted from its glandular site of synthesis at the time of implantation by analyzing uterine flushings obtained from pregnant rats. We report the detection of a significant amount of calcitonin in the luminal secretions collected on day 4 and a lower amount on day 5 of gestation, whereas similar samples collected from animals on either day 3 or 6 of gestation did not contain detectable amounts of this peptide hormone. A transient burst of calcitonin secretion into the uterine lumen therefore occurs immediately preceding implantation. Based on these results, we propose that calcitonin is a measurable marker that forecasts the receptive state of rat endometrium during blastocyst implantation.

High levels of gastrin stimulate the synthesis and secretion of calcitonin…
Iodine-123 salmon calcitonin, an imaging agent for calcitonin receptors: synthesis, biodistribution, metabolism and dosimetry in humans

AP essay questions - Biology Junction

If you don't remember its histology and physiology -- follicles full of colloid, iodine traps, microvilli, parafollicular C-cells, thyroxine=T4, iodotyrosine precursor compounds, triiodothyronine=T3, calcitonin (remember it'sfrom the parafollicular cells that aremostly in the upper lobes), synthesis and endocytosis of thyroglobulin,TRH, TSH=hTSH=thyrotropin, etc.

Chemistry and Synthesis Calcitonin is a polypeptide chain with 32 amino acids. Its molecular weight is about 3,400. It is synthesized from procalcitonin

Calcitonin gene-related peptide (CGRP) ..

The effect of calcitonin (CT) on adenosine-5'-triphosphate (ATP) synthesis in the hepatic mitochondria of rats was investigated. Administration of CT (80 MRC mU/100 g body weight) produced a marked elevation of ATP content in the hepatic cytosol. This increase was completely inhibited by administration of 2, 4-dinitrophenol (0.1 mg/100 g), an inhibitor of oxidative phosphorylation of mitochondria. Verapamil (1.0 mg/100 g) also inhibited the hormonal effect on hepatic ATP content. Moreover, administration of calcium chloride (2.0 and 4.0 mg Ca2+/100 g) elevated the cytosolic ATP content by about 1.8-and 2.3-fold, respectively. Meanwhile, administration of CT produced a remarkable increase of ATPase activity in the hepatic mitochondria. Calcium contents in both the liver and the mitochondria were raised by CT administration. The removal of the mitochondrial calcium by washing with 10 mM ethyleneglycol-bis (2-aminoethylether) -, , ', '-tetraacetic acid (EGTA, pH 7.4) caused complete loss of the increase in mitochondrial adenosine triphosphatase (ATPase) activity induced by CT administration. The CT-increased ATPase activity was appreciably increased by addition of 10 and 50 μM Ca2+, but this increase was not altered by addition of 10 μM trifluoperazine or calmodulin (2.5 μg/ml). These results suggest that CT stimulates ATP synthesis in the hepatic mitochondria, and that the hormonal effect may be mediated through calcium, but not calmodulin.

Exogenously added calcitonin (CT) induces DNA synthesis in serum-starved prostate cancer LNCaP and PC-3M cells.

Anti-Calcitonin Gene Related Peptide antibody produced in rabbit.